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Carbon fibers

The group “Carbon fibers” has its focus on the investigation of carbon fibers along the complete process chain – starting at the precursor fiber, over the stabilized fiber, to the carbon fiber. Especially the development and changes of the microstructure and the chemical structure of the fibers is investigated. The ultimate aim is a fundamental understanding of the physical and chemical processes during stabilization and carbonization. In particular, a correlation between the obtained microstructure and the mechanical properties of the carbon fibers are of high interest.

Investigation of bulk fiber properties

Transmission electron microscopy on carbon fibersOne research focus is the investigation of the bulk properties of carbon fibers and their precursor materials. Of interest are the microstructure, the crystallinity, the chemical composition and the binding properties as well as defects of the fibers possibly developing along the production chain. Those microscopic properties are of crucial importance for the mechanical properties of the resulting carbon fibers. To analyze the orientation and the lattice distance of crystalline graphite planes and the size of coherent domains, microscopic methods with high lateral resolution are used, e.g. transmission electron microscopy. The chemical structure of the fiber volume is investigated by spectroscopic methods, e.g. infrared spectroscopy or scanning auger microscopy. The crystallinity is analyzed by X-ray diffraction.

Investigation of the fiber surface

Scanning electron microscopy on carbon fibersImportant for the adhesion between carbon fibers and polymer matrix – so called fiber matrix interaction – are the properties of the fiber surface, e.g. the chemical composition and the microstructure. Especially the investigation of the sizing of carbon fibers is of interest, which is used to improve the adhesion between fiber and matrix. Another important aspect is the topography of the fiber surface, in particular the fibrillar structure, the roughness and pores, which is analyzed by scanning probe microscopy. The identification of functional groups and the influence of surface activation are investigated by scanning auger microscopy and photoelectron spectroscopy.

Thermophysical investigation of the stabilization process

The stabilization process, which describes the conversion of a thermoplastic precursor fiber to an unmeltable fiber, is crucial for the properties of the resulting carbon fiber. Thermophysical investigations of the precursor fibers aim for an understanding of the chemical and physical changes, which take place during the stabilization process. Possible methods are differential scanning calorimetry or thermogravimetric analysis.

Contact person:

Judith Moosburger-Will

Group members:

Matthias Bauer

Bastian Brück

Patrick Gutmann

Robert Horny

Christina Kunzmann

Elisabeth Lachner